Quick definitions from WordNet (activity)▸ noun:any specific activity ("They avoided all recreational activity")▸ noun:(chemistry) the capacity of a substance to take part in a chemical reaction ("Catalytic activity")▸ noun:the trait of being active; moving or acting rapidly and energetically ("The level of activity declines with age")▸ noun:the state of being active ("His sphere of activity")▸ noun:an organic process that takes place in the body ("Respiratory activity")▸ noun:a process existing in or produced by nature (rather than by the intent of human beings) ("Volcanic activity")